title: Endurance training modulates intramyocellular lipid compartmentalization and morphology in skeletal muscle of lean and obese women.
abstract: BACKGROUND
  The accumulation of intramyocellular lipids (IMCLs) and mitochondrial dysfunction in skeletal muscle have been associated with insulin resistance in obesity. Endurance training (ET) increases mitochondrial content/activity and IMCL content in young, active men and women. We have previously shown that ET alters the size, number, and physical juxtaposition of IMCLs and mitochondria.
  
  
  OBJECTIVE
  The purpose of this study was to determine the effects of obesity and ET on mitochondrial function, IMCL content, and IMCL-mitochondria juxtaposition in sedentary lean and obese women. DESIGN, SETTING, SUBJECTS, INTERVENTION, AND MAIN OUTCOME MEASURES: Obese (n = 11) and lean (n = 12), sedentary women were recruited using local advertisements and underwent 12 weeks of ET in our training facility at McMaster University. Blood and muscle biopsy samples (vastus lateralis) were collected before and after ET to measure IMCL and mitochondrial ultrastructure, mitochondrial oxidative capacity, lipid oxidation capacity, and lipid metabolism by-products.
  
  
  RESULTS
  Obese women were insulin resistant (homeostasis model assessment of insulin resistance) compared with lean women. ET did not change body weight but increased mitochondrial oxidative and β-oxidation capacity in both groups. ET mediated reorganization of the muscle architecture, whereby IMCL content in the subsarcolemmal region was reduced with a concomitant increase in intermyofibrillar IMCLs. ET increased the percentage of IMCLs in direct contact with mitochondria and did not alter diacylglycerol and ceramide content in either group.
  
  
  CONCLUSIONS
  ET mediated positive changes in mitochondrial function and lipid oxidation and induced intracellular IMCL reorganization, which is reflective of greater IMCL turnover capacity in both lean and obese women.
authors.affiliation: Departments of Pediatrics and Medicine, McMaster University, Neuromuscular Disease Clinic, Health Sciences Centre, Room 2H26, 1200 Main Street West, Hamilton, Ontario L8N 3Z5, Canada. tarnopol@mcmaster.ca.
authors.forename: Michaela C
authors.initials: MC
authors.lastname: Devries
authors.forename: Imtiaz A
authors.initials: IA
authors.lastname: Samjoo
authors.forename: Mazen J
authors.initials: MJ
authors.lastname: Hamadeh
authors.forename: Colin
authors.initials: C
authors.lastname: McCready
authors.forename: Sandeep
authors.initials: S
authors.lastname: Raha
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Watt
authors.forename: Gregory R
authors.initials: GR
authors.lastname: Steinberg
authors.forename: Mark A
authors.initials: MA
authors.lastname: Tarnopolsky
mesh_terms: D000328:Adult; D001642:Bicycling; D015415:Biomarkers / Q000097:blood / Q000378:metabolism; D015992:Body Mass Index; D002518:Ceramides / Q000378:metabolism; D004075:Diglycerides / Q000378:metabolism; D015444:Exercise; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D050356:Lipid Metabolism; D008875:Middle Aged; D008931:Mitochondria, Muscle / Q000378:metabolism / Q000648:ultrastructure; D063269:Mitochondrial Turnover; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000648:ultrastructure; D009765:Obesity / Q000097:blood / Q000378:metabolism* / Q000473:pathology / Q000628:therapy; D010085:Oxidative Phosphorylation; D010807:Physical Endurance; D052097:Quadriceps Muscle / Q000378:metabolism / Q000648:ultrastructure; D012519:Sarcoplasmic Reticulum / Q000378:metabolism / Q000648:ultrastructure; D013851:Thinness / Q000097:blood / Q000378:metabolism* / Q000473:pathology / Q000628:therapy; D055815:Young Adult
chemical_list: D015415:Biomarkers; D002518:Ceramides; D004075:Diglycerides